Various types of microphones and receivers have been used through the years. In these devices, different electrical components are housed together within a housing or assembly. For example, a microphone typically includes micro-electromechanical system (MEMS) device, a diaphragm, and integrated circuits, among other components and these components are housed within the housing. Other types of acoustic devices may include other types of components.
One characteristic that is used to define whether a microphone is operating properly is its sensitivity. The sensitivity of a microphone is typically determined by transmitting sound energy into the microphone and then measuring the response of the microphone, for example, its output voltage. Although sensitivity can be measured in a variety of different units, in one example, it is measured in units of “dBV/Pa” (As is known, 1 Pa=94 dB re 20 μPa).
Various manufacturers of different products (e.g., cell phones, personal computers, and hearing aids to mention a few examples) utilize microphones. Typically, the manufacturer selects a nominal sensitivity as the acceptable sensitivity for the microphones that it is using. Additionally, the manufacturer may provide a sensitivity range in which some variation of sensitivity is allowed. That is, if the sensitivity of an individual microphone is not required to be exactly at the nominal sensitivity; if the sensitivity falls within the range, the microphone is deemed to still have acceptable performance. To take one specific example, a nominal sensitivity may be X dBV/Pa and this be allowed to vary in a range of X +/−3 dB (X−3 dBV/Pa to X+3 dBV/Pa).
In recent years, the sensitivity ranges give by many manufacturers have been tightened into smaller ranges in order to provide for improved performance. Unfortunately, these tightened ranges have resulted in more devices falling outside the range. Consequently, when a device falls outside the acceptable range the manufacturer typically rejects the part resulting in the need to obtain a replacement part thereby increasing costs. Additionally, dissatisfaction with the suppliers of the microphones has also occurred when too many parts were found to have an unacceptable performance. No previous approach has been provided that adequately addresses these problems.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.